Rubber nipple



FIG. 1 is a perspective view from above in accordance with the design;

FIG. 2 is a left side view thereof;

FIG. 3 is a top view thereof;

FIG. 4 is a front elevation view thereof;

FIG. 5 is a right side elevation view thereof;

FIG. 6 is a rear elevation view thereof; and,

FIG. 7 is a bottom view thereof.

The broken lines in the drawings represent unclaimed environmental subject matter and form no part of the claim. 

CLAIM The ornamental design for a rubber nipple, as shown and described. 